The first mechanical embodiments for separating two semiconductor substrates worked primarily with blades, wires or fluid jets, in particular water jets, which were inserted, pushed through or sprayed into the interface between the two substrates. This approach routinely results in at least partial destruction of the surface of at least one of the two substrates. The scratching of a substrate surface is primarily problematic for substrates that are coated and provided with functional units.
Other proposed solutions for separating two semiconductor substrates that are connected to one another in particular via an adhesive layer tracked a full-surface attachment of both substrates to their surfaces. The removal of a substrate by a (surface) force that only acts normally is technically difficult to carry out, since the adhesive strength routinely results in an at least partial destruction of the substrate.
Another separation approach was disclosed in the patent specification WO2013/091714A1. The patent specification discloses an annular, flexible tool, with which two substrates can be separated from one another by a peripheral collar of an inner side of a ring that opens on one side enclosing the peripheral edge of a first substrate. The bending moment of the annular tool allows a continuous controlled detachment of the upper substrate from a lower substrate beginning from a point on the side of the substrate stack. The production of the flexible tool is extremely expensive, however, since the peripheral collars must be fabricated with very tight tolerances. The tight tolerances are necessary in order to enclose the peripheral edges of the substrate exactly. If the peripheral collars are too large, the peripheral edge of the substrate slides from the peripheral collar; if it is too small, the peripheral edge of the substrate can really not be enclosed at all. In addition, not all substrates are made the same. Substrates can in general have different thicknesses and different, albeit standardized, peripheral edges, hi general, therefore, the peripheral collars must always pass into the respectively used type of substrate.